what you have
From what I see, The thing on the roof is called a condenser, After the refrigerant goes inside and is used to cool the air, the gas goes back to the compressor, then after that goes through the condenser, that drops the temp of the gas and goes back to a liquid. from the condenser, the liquid goes through tiny little holes and is back to a gas with low temperature.
If you get rid of the condenser on the roof you would have to put another one on the bus skirts or in the nose. The ceiling mount units do not all have to be used but the condenser, compressor, is sized for that useage. You have a big system there. I would assume the bus came from some place warm/hot.
the ceiling mounts, take the covers off first. You will find some wires and two pipes, little pipe and big pipe.
you have two ways to get the refrigerant out of the system, responsible way, and the easy way. Find some automotive a/c place and ask them. Look on line about how to remove refrigerant.
Unplug / cut wires remove line fittings from ceiling units, unbolt units from ceiling.
The part on the roof is likely to weigh a couple of hundred pounds.
I dont know if compressors are engine mounted, most likely, or roof mounted and electric- possible but not likely.
does this help at all?